The transition from adolescence to adulthood and employment is a significant challenge for the 8 million Americans living with intellectual disabilities. Up to 85% of people with ID (PwID) face unemployment as adults despite receiving support services through a variety of local, state, and federal mechanisms. A critical limitation exists in our ability to appropriately and accurately assess and predict the best fit between individuals' skills and interests and job demands and activities. A valid and reliable method that both informs employment services and predicts problems is needed to target supports, preventing job loss, and keeping PwID employed. We developed the Vocational Fit Assessment (VFA), to provide accurate, person-centered measures of work-related interests and adaptive behavior (Persch, 2015). The VFA consists of the: (1) VFA-Worker and VFA-Job, which are used to assess workers' abilities and job demands, respectively, using common item stems; (2) Demands & Abilities Transforming Algorithm, which transforms VFA data for analysis and clinical action; and (3) Job Matching Reports, which visualizes vocational fit ?VocFit? by identifying the pros and cons of each potential job match and areas of need that are suitable for intervention (e.g., job training, accommodations, modifications). Stakeholders (e.g., PwID, parents, providers, employers) engaged in the shared decision-making process central to customized employment may use VFA data to guide intervention, target potential problems, and monitor response to intervention. Our long-term goal is to improve employment outcomes for PwID. The overall objective of this project, which is the next step to achieve our long-term goal, is to quantify the reliability, validity, responsiveness, and clinical utility of the VFA with PwID in diverse special education and vocational rehabilitation settings. We will accomplish this objective by pursuing the following specific aims: Specific Aim 1: Quantify Vocational Fit Assessment reliability and validity in the context of PwID in transition to employment. Specific Aim 2: Determine Vocational Fit Assessment responsiveness. Specific Aim 3: Evaluate Vocational Fit Assessment clinical utility. We will utilize mixed-methods approaches to achieve these aims. A Comprehensive Assessment Battery (CAB) including the VFA, criterion employment measures, and proxy measures will be administered through an interview with the participant PwID (n=360) and those who know them well (i.e., reliable reporters) on 3 occasions (baseline, after 12 months, and after 24 months). Psychometric evaluation of the VFA using factor analysis, Rasch analysis, and multivariate multilevel growth curve modeling will follow data collection. The CAB data, interviews, and focus groups with disability and employment experts will be used to define meaningful anchors. This approach enables evaluation of VFA responsiveness to change using anchor and distribution-based methods when combined with administration of the VFA on multiple occasions.